When an oil or gas well produces water (generally with a large content of dissolved salts), there is a possibility for scale to form. This may also occur in facilities where water injection is used as an improved recovery system, or when using gas with high CO2 content and other components. Buildup of mineral deposits or incrustations may occur in pipes and equipment both on the surface and in the bottom of the well, or even inside the porous medium in the formation of the oil deposit itself. Buildup of scale deposits can result in significant reduction in oil production or even full blockages in pipes, and exacerbate corrosion on the surfaces of equipment used to handle and process such produced fluid.
As an example, oil and gas pipelines, including subsea pipelines, typically carry production fluids from the production wells (including subsea wells). The presence of calcium in the produced water from hydrocarbon extraction can result in the formation of inorganic and organic salts (known as scales) that may impede production of hydrocarbons or limit the ability to manage water in surface facilities and subsurface injection facilities. Ongoing deposition of scale in pipelines and equipment can result in production and injection impairment, flow restrictions, process upsets, and operational issues (e.g. malfunction of valves).
One common method for scale control is the injection of scale inhibitor chemicals. Scale inhibitors prevent the formation of large deposits of mineral scale that would otherwise form rapidly when the brine is oversaturated with respect to a specific scale type. The use of scale inhibitor chemicals for calcium scale control is most common in brines with low to moderate pH of ˜4-7.
The application of scale inhibitor treatment is varied according to the location. Despite the widespread use of scale inhibitors, there are a number of operating conditions where the use of conventional scale inhibitors may not be viable and alternative strategies are required.
There is a need for improved compositions and methods to inhibit scale formation, deposition, and adherence thereof.